Maybe their personal society is beyond the need of needing money for personal things and instead most money goes on at a governmental level? I don't know! There clearly were not enough books on Andalites.

I was sort of wondering if they are actually a communist society and maybe money's something they don't think about unless they're working with other aliens. That would explain why Ax and Elfangor thought the concept was weird, but characters that were Yeerks wouldn't.

Yeah, their military designations were also weird. At least, at that level. Most of the terms were basically what we call ourselves (captain, commander, etc.) But 'prince'? It seemed mostly like an honorary title/privilege level in the military.